Study Of The Wear-resistance Properties Of The Non-smooth Brake Disc/Lining Concave Surface

With the rising Chinese economy, people's living level greatly improves and the number of vehicles rapidly increases. The braking system, an important composition of the car, has drawn much more attention in its safety and durability. Brake disc/piece is the friction part of the braking system, whose severe abrasion would lead to serious safety accidents and property loss. The previous investigations on improving the wear resistance of the brake disc/piece mainly focus on modifying the fabrication materials, which has some shortcomings and limitations. Recently, the non-smooth bionic surface has emerged as an interesting alternative to the abrasion technology. Bionics research found that the geobiont such as dung beetle can shuttle in the soil over a long period without any damage of the body surface, indicating the good wear resistance. It is found that the animal body surfaces are non-smooth, which are formed in the hundred million years of evolution and can effectively solve the wear problem when applied to the brake disc/piece. Proceeding from the bionics, this paper studied the wear resistance of the non-smooth surface and apply the concave surface with good wear resistance performance to the brake disc/piece. The non-smooth surface wear mechanism is revealed and the surface morphology of the concave surface with optimal wear performance.The non-smooth concave surface of the dung beetle was selected as the bionic prototype. The different arranged concaves on the brake disc were laser processed on the SilMark-WT workbench. The distances between the concaves are selected to be 1 mm?1.25mm?1.5 mm, while the diameters are 0.4 mm?0.6 mm?0.8 mm, respectively. The materials of the brake disc and brake lining are cast iron and semimetal, respectively. The wear experiments were performed on the omnipotence wear testing machine of MMW-1. The wear capacity was measured by the L-200 photoelectric analytical balance. The experimental result is processed by range method and shows that the diameter is the main factor influencing the wear capacity while the distance is less important. The best combination is the distance of 1 mm with diameter of 0.8 mm. Orthogonal polynomial regression design was adopted to optimize the regression equation, which is: y=5.006+1.4Z1-2.5Z2It is indicated that the distance between the concaves and concave diameter both have significant influence on the wear capacity. However, the effects of the distance and diameter don't interact. The wear capacity of the smooth and non-smooth surface is compared. The relative performance improvement of 65.85% of the non-smooth surface compared with that of the non-smooth was obtained based on the best combination of the distance and diameter. And the non-smooth concave surface has influence on friction coefficient.The ANSYS12.0/LS-DYNA software was employed to dynamically simulate the brake disc/piece braking process.9 types of non-smooth surfaces and 1 type of smooth surface are designed for experiments. Von Mises stresses under ten different conditions are explored. According to the statistical analysis of every two steps out of the 100 steps within the simulation time scope, the fluctuation situation of the Von Mises stress of the smooth and non-smooth brake disc in friction experiment was obtained. The results show that the fluctuation of the Von Mises stress of the non-smooth discs was smaller than that of the smooth one except one of those. The comparison of the Von Mises stress of the smooth with non-smooth surfaces in the middle time indicates that the position with larger stress of the smooth surface focuses on the contact surface of the two test specimen, while the Von Mises stress of the concave surface dispersed the Von Mises stress on the whole brake disc lower surface, improving the stress concentration phenomenon and reduce the heat of friction. Furthermore, the shear stress ?xy on the smooth discs and non-smooth discs with different pits was investigated, which shows that the shear stress focuses on the concaves of non-smooth discs, which is much smaller than that of the smooth discs. The area with large shear stress of the non-smooth disc is smaller than that of the smooth disc. For the non-smooth concave surface with concaves of the same diameter, the shear stress increases with increase of the distance between the concaves, while for the that with same distance between the concaves, the shear stress decreases with the concave diameter.The ANSYS14.0/Workbench software was employed to dynamically simulate the simplified brake disc/piece model. Comparing the Von Mises stress and the contact stress of the smooth and the best non-smooth surfaces at the beginning?middle and end position. The best concave is compact and uniform on the brake disc surface.Because of the existence of concave, stress of the brake disc/piece is more uniform. It improves the stress concentration phenomenon and the wear resistance.